The GNSS (Global Navigation Satellite System) technology can provide stable and accurate location information for users around the world and has been widely used in the aviation field. The users mainly need the following navigation performance indicators during use of global satellite navigation: accuracy, integrity, continuity and availability. RAIM (Receiver Autonomous Integrity Monitoring) can provide service for horizontal navigation in an approach phase of an aircraft. ARAIM (Advanced Receiver Autonomous Integrity Monitoring) is a new generation of satellite navigation integrity monitoring technology that extends the conventional RAIM. ARAIM uses multiple GNSS constellations and dual frequencies, has a multi-fault monitoring capability, and therefore, can support vertical navigation below the height of 200 feet (LPV-200). In order to achieve this goal, an aeronautical receiver needs to consider possible failures of each satellite. The computational load is increased while satellite subsets are selected according to this rule. Before use of satellite navigation, a user should predict the availability of an ARAIM algorithm. Satellite navigation is used when ARAIM meets required availability demands, otherwise, satellite navigation is abandoned, and other navigation devices are used.
Satellites of a BeiDou constellation have the characteristics of a hybrid orbit. After completing global networking, the BeiDou constellation will consist of 35 satellites, including 5 GEO (Geostationary Orbit) satellites, 3 IGSO (Inclined Geosynchronous Satellite Orbit) satellites, and 27 MEO (Medium Earth Orbit) satellites. For users in the Asia-Pacific region, the current BeiDou regional constellation is non-uniform and more concentrated in constellation configuration. Therefore, during fault assumption of the satellites, if fault situations of all the BeiDou satellites are considered on average, it is bound to cause that some extreme assumptions greatly impact analysis results and even make the analysis results unavailable.
Thus, in order to solve the above problems in the prior art, an ARAIM subset selection method and system based on a BeiDou constellation are required to modify a subset of the BeiDou constellation for better availability prediction.